A number of platforms to detect molecular biomarkers have been developed, creating tools to probe complex biological systems. These approaches have been based on various sensing techniques including nuclear magnetic relaxometry, mass spectrometry, holographic imaging, fluorescence detection, microfluidic sorting and sensors based on surface plasmon resonance, colorimetry, magnetoresistance, electrical impedance, and field-effect gating. It remains challenging, however, to resolve sparse cells or scant biomarkers in native samples that are abundant with host cells. Accordingly, extensive sample preparation and purification processes may need to be employed, which can lead to the loss of target cells and/or the decay of molecular biomarkers, thus inhibiting routine clinical use.